Language is our signature human cognitive skill. Yet, many critical questions regarding the brain basis of language and the role of specific cortical regions in linguistic behavior remain unanswered. Recent research demonstrating high anatomical and functional variability in human brains, and in particular in the frontal lobes, suggests that group averaging analyses - applied in the vast majority of the past language studies - may not be optimal. I propose to apply the individual subjects fMRI approach to the study of the functional architecture of the language system. I expect this approach - which has proven very powerful in revealing the fine-grained functional organization of extrastriate visual cortex - to reveal functional organization in language cortex that has not been apparent in prior group-based studies. Informed by prior work in on-line language processing and theoretical linguistics, I will tackle two fundamental questions about the functional architecture of the language system: i) does language processing engage domain-specific mechanisms specialized for language per se (the Domain-Specific Hypothesis), or does it rely on more general-purpose processing machinery that is also engaged in non- linguistic processing (the Domain-General Hypothesis)?;and ii) what is the internal functional organization of the language system: do different aspects of language processing (e.g., syntax and semantics) engage the same cortical regions (the Shared Language Components Hypothesis), or do they engage distinct cortical regions (the Specific Language Components Hypothesis), and if so where do these regions reside in the brain? Developing reliable ways of localizing different language functions with fMRI will help in pre- operative planning for patients with tumors and patients diagnosed with epilepsy. Successful pre-operative localization of critical language regions will reduce the average surgery duration and facilitate the post- operative recovery process.